Phase III Trial of Tamoxifen Alone vs. Tamoxifen Plus Radiation Therapy for Good Risk Duct Carcinoma In-Situ (DCIS) of the Female Breast

RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. Estrogen can stimulate the growth of breast cancer cells. Hormone therapy using tamoxifen may fight breast cancer by blocking the uptake of estrogen by the tumor cells. It is not yet known if radiation therapy is more effective than observation, with or without tamoxifen, in treating ductal carcinoma in situ. PURPOSE: Randomized phase III trial to compare the effectiveness of radiation therapy with that of observation, with or without tamoxifen, in treating women who have ductal carcinoma in situ.